Generally, it is, at least to a minimal degree. It is not too bad to get a UPS that can keep a computer going for 10 to 20 minutes. Getting something that can go for an hour costs a lot more. And the little bricks that you use for a single PC would be useless on a 19" rack of a dozen servers, so those use specialty (very expensive) UPS's. So, in the end, it all comes down to how much power your company is willing to pay for.

Plus, there is more to it than that. At my company, all Unix systems and all servers have backup power, so my computer can still run in the dark (for a little while). But none of the networking gear has any sort of backup, so a one-second power glitch will kill the routers. We use a Citrix server to get Windows applications on Uniix boxes. When the routers die, the connections get broken, and everything on the Windows side locks up. No fun.